Furnace thermostat control



June 6, 1933. L PERSONS 1,912,791

FURNACE THERMOSTAT CONTROL Filed Aug. 8, 1950- 1 J In vez zfai" Z (raw/waif 1 67380233 618 Jzfiorneyq Patented June 6, 1933 LAURENCE PERSONS, OF ST. LOUIS, MISSOURI FURNACE THERMOSTAT CONTRQL Application filed August 8, 1930. Serial No. 473,894.

My invention relates to improvements in control means for furnaces and the like. One ob ect is the provision of thermostatic means,

responsive to furnace temperature, for supplementing an ordinary thermostat for preventing overheating of, a furnace. Other objects will appear from time to time in the course of the specification and claims.

I illustrate my invention more or less diagrammatically in the accompanying drawing, wherein Figure l is a side elevation with parts in section, and including a wiring diagram;

Figure 2 is a. section on the line 22 of Figure 1;

Figure 3 is a section on the line 33 of Figure 2:

Figure 4 is a section on the line 4-4 of' Figure 3; and

Figure 5 is a section on the line 5-5 of Figure 4.

Like parts are indicated by like symbols throughout the specification and drawing.

Referring to the drawing, dicates a furnace or the like which may include the flue pipe A and the hot air inlets A A indicates a door for the furnace and dA a draft door. A indicates a check draft oor.

B diagrammatically indicates a draft control mechanism, the details of which form no part of the present invention, but which includes the lever arms B and B The lever arm B is connected by the flexible connection B with the door A". And the lever B is connected by the flexible connection B with the door A. B diagrammatically indicates a room thermostat as in circuit as by the conductive connections B with any suitable electric operating mechanism associated with the control means B. B indicates a trans- V former, and B conductive connections between the transformer and any suitable source of electric power. It will be understood that in response to varying temperature conditions and to the actuation thereby of the thermostat B, the lever arms B and B are actuated to control the doors A and A. From the position in which they are shown in Figure 50 1, it will be understood that the check draft A generally indoor A is opened and the draft door A is closed, which position will be maintained until the room temperature falls to such a point as again. to actuate thethermostat B and to cause a reversal of the positions of the two doors.

C diagrammatically indicates a supplemental thermostat member and its associated parts. It mayinclude, forexample, the base plate C upon which is mounted a housing 0 connected thereto as by the pins or corn nections C Positioned within the housing C is the base C of insulating material. Pivoted for rotation in relation to the plates C C and the base C is the shaft or pin C the lower end of which penetrates in an aperture C in the plate C and through the aperture C in the furnace wall. Downwardly extending from the plate C is a pin 0*. Secured at one end of the pin C and secured at the other to the pin or shaft C is a bimetallic coil O". It will be understood that this coil flexes iii-response to changes of temperature to which it is subjected, thus causing rotation of the shaft or pin. 0". The size of the aperture C is such that the memher 0* may pass therethrough to permit easy installation and removal of the assembly herein described.

I Rotatably positioned upon the base C is the arm D also of insulating material; The arm D is mounted concentrically for rotation with the pin C but is rotatable in relation thereto. Thepin C is provided at its upper end with a head D fixed against rotation in relation thereto. The head D is provided with an upstanding lug D Pivotally mounted on the upper end of the pin C is a yoke D Between the yoke D and I the head D is positioned a spring D, one end of which engages the upstanding lug D5. The tendency of this spring is to cause rotation of the yoke D in relation to the pin C. c D indicates an insulating plug associated with the yoke D. To it is secured the conductive arm or leaf D", one end of which is opposed to the permanent magnet D mounted upon the arm D. Associated with the permanent magnet is an adjustable contact element D which in turn is opposed to a contact D at the end of the leaf D.

, arm D.

contact D opposed to E indicates a cover for enclosing and protecting the mechanism upon the plate 0 It will be realized that whereas I have described and shown a practical and operative device that nevertheless many changes may be made 'in size, shape, number and disposition of parts without departing from the spirit of my invention. I therefore wish my drawing to be taken as in a broad sense illustrative and diagrammatic, rather than as limiting me to any precise showing herein, except so far as I limit myself specifically by the language of my claims.

The use and operation of my invention are as follows: i I

The supplemental thermostat control herein described is adapted to be associated directly with the furnace and includes a thermostat member, for example the bimetallic coil or srip C", which is subjected more or less directly to the heat of the furnace or of the hot water, steam or air delivered by the furnace or heater. The device is associated with thefurnace or heater structure itself and serves to prevent overheating. As an ex ample, if an oversize furnace or heating plant 15 employed in a small house, my supplementa-l control prevents overheating of the furnace, even though the normal room temperature thermostat control B may fail to function. A good example is where a window is left open and blows cold air onaroomthermostat, or that the room thermostat may call for heat and may make or break a heating circuit, even though the furnace is'actually overheated.

I illustrate the coil G as positioned within the bonnet or top of a furnace with the switch mechanism on the outside and the bimetallic member positioned within the wall of the furnace. The make and break mechanism of the switch, including the contacts I) and D is in series with the room thermostat. The shaft G is adapted to be rotated by movement of the coil C in response to changes of the tem erature to which the coil is subjected. ovement of the coil rotates the shaft C in a given direction and may move the pin D against the opposed stop portion D of the yoke D thereby rotating the movable switch leaf D", This switch leaf'may normally be held with its the contact D as by the action of the spring D", and also by the action of the permanent magnet D". The purpose of the permanent magnet is to pro vide a quick break, the contact being normally urged against it by the side spring. The permanent magnet. is mounted on the adjustable arm D and the opposed spring contact member D is separately mounted on the pivoted yoke D Thus rotation of the shaft C moves the pin D against spring pressure and breaks the contact in response to an increase in temperature. On the other hand, a decrease in temperature causes counter rotation of the shaft, but this counter rotion does no damage and merely rotates the pin I) out of contact with the opposed stop caving the contact 1) spring thrust in contact with the permanent magnet and the electric contact I)". The calibration of the base C serves as a dial, so that the normally fixed contact D may be set at any desired position. Assuming that it is set at a predetermined position to actuate the device at a predetermined temperature, it is then not disturbed and the fixed contact D remains constantly positioned. When the temperature within the furnace reaches a predetermined point, the bimetallic coil C rotates the shaft C and forces the contact D away from the opposed contact D The permanent magnet provides the desired snap or quick action. hen the circuit is broken between D and D", it breaks the connection between the room thermostat B, through the conductive connections B to the actuating device 0, and makes the actuating device B respond to the increase in temperature of the furnace regardless of what may be the indication of the room thermostat. Without going into details of the control mechanism B, it will be understood that when the circuit B is broken, the lever arms B and B normally are caused to take the position in which they are shown in Figure 1, closing the draft door A" and opening the check A It will be understood that while I have shown my invention as applying to a hot air furnace, it may be used with other heaters, for example with water vapor and steam heaters.

I claim:

1. A temperature responsive control element comprising abase plate, a plurality of studs secured to one face thereof, and extending therefrom, a switch supporting plate secured to the free ends of the studs, a switch member mounted on the switch supporting plate, temperature responsive means mounted on the opposite faces of the base plate, said base plate and switch supporting plate being provided with aligned apertures, and an operating connection between the temperature responsive means and said switch member extending through said apertures.

2. A temperature responsive control element comprising a base plate, a plurality of studs secured to one face thereof and extending therefrom, a switch supporting plate se cured to the free ends o the studs in spaced relation to the base plate, a switch member mounted on the switch supporting plate, a studmember secured to the opposite face of the base plate, temperature responsive means mounted upon said stud in spaced relation to the base plate, said base plate and switch supporting plate being provided with aligned apertures, and an operating connection between the temperature responsive means and said switch member extending throu h said apertures.

- 3. 5 tem rature responsive control element comprising a base plate, a switch membermounted in spaced relation to one face of the base plate, said switch member including a stationary contact and a movable contact, means for relatively adjusting said contacts to vary the point at which they open and a close, temperature responsive means mounted on the opposite face of the base plate, and an operating connection between the temperature responsive means and the switch member, a lost motion connection between said connection and the movable switch contact, and resilient means biasing the movable switch contact to closed position.

Signed at St. Louis, Missouri,this 4th day of August 1930.

LAURENCE M. PERSONS. 

